//捕获器不等式用于限制捕获器过于反常的返回行为。
const target = {
  'qaz':"smith"
};
Object.defineProperty(target,'foo',{
  configurable:false,
  writable:false,
  value:'bar'
})
const handler = {
  get(){
    return 'hello world';
  }
}
const proxy = new Proxy(target,handler)
console.log(proxy.qaz);//hello world
console.log(target.qaz);//smith
console.log(target.foo);//bar
// TypeError: 'get' on proxy: property 'foo' is a read-only and non-configurable data property on the proxy target but the proxy did not return its actual value (expected 'bar' but got 'hello world')
console.log(proxy.foo);
